It's the latest sign of a rocky relationship between the financial regulator and Groupon, a popular online "daily deals" coupon service. Groupon and SEC regulators exchanged a series of contentious emails in the run-up to Groupon's IPO last fall, the blog Silicon Beat reports.

Less than five months after its IPO, Groupon announced Friday it was revising fourth-quarter results to show a bigger net loss and lower revenue, Reuters reports. The company also cited a "material weakness" in how the company oversees its financial statements.

That "weakness" is being addressed, and will likely be publicly discussed when Groupon reports its first-quarter earnings in May, sources told the Journal.

A big issue dogging Groupon seems to be a failure to anticipate refunds under "The Groupon Promise." As described on Groupon's website, the promise states, "If Groupon ever lets you down, we'll return your purchase -- simple as that."

But sources told the Journal there were far more refunds than expected in January. Not only were the refunds for higher-priced deals like eye surgery, but Groupon did not have enough money set aside to cover the refunds, the Journal reported.

The SEC's "preliminary" inquiry into Groupon may turn out to be no big deal, Business Insider opines. But the blog also suggests it's "never a good thing" to raise the SEC's eyebrows.

Meanwhile the Silicon Beat blog seems to wag a finger at Groupon's attorneys, as well as its bankers and accountants. "The company has paid them millions of dollars and fees. An investment that hasn't provided a very good return," Silicon Beat said.